JP6718216B2 - Method and apparatus for coating substrate - Google Patents

Description

The present invention relates to a method for coating a substrate with a lacquer and a coating device for applying the lacquer to the substrate.

Microfabrication and nanofabrication processes generally use a lacquer applied as a layer on the substrate to be treated. These lacquers can be used, for example, to form masks on the substrate, which can be used to form the desired structures or to achieve processing on the substrate. For this purpose, the lacquer is, for example, light-sensitive, and the desired structure is transferred from the photomask to the light-sensitive lacquer using an optical image.

For optimum results, it is very important that the applied lacquer layer is free of irregularities (grains) and particles. In addition to spinning methods, spraying methods are also used for applying lacquer on a substrate, in which spraying method the lacquer is sprayed onto the substrate by means of a nozzle. Especially if the substrate has a topography, ie if the substrate itself already has a vertical, three-dimensional structure on the surface, the most likely homogeneous lacquer layer is the spraying-on the lacquer. Can only be achieved economically.

However, when sprayed with lacquer, lacquer particles are formed on the lacquer layer, but a certain number of lacquer drops dry during flight between the nozzle and the substrate, leaving almost dry lacquer particles. , Lacquer present on or at the surface of the substrate. The lacquer particles collect on the spray-on lacquer layer and become a problem during further processing, for example exposure, and become a partial defect on the finally produced substrate.

It is an object of the invention to provide a method and a device in which the lacquer layer applied on the substrate is uniform and free of lacquer particles.

This object is achieved by a method of coating a substrate with a lacquer, in which the lacquer is sprayed on the substrate and then the lacquer applied on the substrate is sprayed with a solvent.

Subsequent spraying of a solvent onto the applied lacquer flattens the irregularities formed on the substrate, decomposes the lacquer particles adhering to the substrate and makes the surface of the substrate flat (at least essentially). The lacquer particles are gone.

The term "lacquer" in this context is understood to be a mixture of solvent and lacquer suitable for the desired application.

Preferably, the solvent is partly sprayed onto the applied lacquer, which allows a controlled aftertreatment of the lacquer.

In one embodiment, between the spraying of the lacquer and the application of the solvent to the applied lacquer, the solvent ratio of the applied lacquer is reduced and the applied lacquer is fixed. The term "set" is understood here to mean that the viscosity of the applied lacquer increases and the applied lacquer no longer flows until further processing. Especially when the substrate has a topographical shape, it is important to fix the lacquer and keep the edges and slopes of the substrate reliably covered by the lacquer.

Until and during the application of the solvent, the solvent ratio of the applied lacquer should, on the one hand, be kept in a range which ensures that the viscosity of the applied lacquer is sufficiently high to prevent the lacquer from flowing any more. There must be. On the other hand, the solvent proportion should not be reduced to such an extent that during spraying of the solvent the lacquer particles and irregularities are no longer decomposed or flattened.

The substrate and/or the applied lacquer are preferably heated during and/or after spraying the lacquer, whereby the solvent proportion of the applied lacquer can be reduced in a simple manner.

In one embodiment of the invention, the lacquer is applied to the substrate according to a predetermined spray pattern, preferably in parallel, where the solvent is also sprayed onto the lacquer, which is also applied according to the spray pattern. .. This ensures that the applied lacquer is sprayed with the solvent.

Preferably, the time between the time when the lacquer is applied on the position on the substrate and the time when the solvent is applied at this position is such that when the solvent is applied, the applied lacquer is It ensures that they always have the same solvent ratio.

In one embodiment of the invention, the lacquer is sprayed on the substrate by means of a lacquer nozzle and the solvent is sprayed by means of a solvent nozzle separated from the lacquer nozzle, which makes the substrate quick and effective. Can be lacquered.

Preferably, the lacquer nozzle and the solvent nozzle are moved above the substrate in parallel to the substrate, in particular simultaneously, requiring one drive mechanism for the two nozzles.

In a preferred embodiment, when the lacquer nozzle and the solvent nozzle move, the solvent nozzle follows the path of the lacquer nozzle, which is set to ensure that the sprayed lacquer is subsequently sprayed with solvent. It

In a variation of one embodiment, the lacquer nozzle and the solvent nozzle move in at least one plane parallel to the substrate in parallel paths above the substrate, where the distance between the lacquer nozzle and the solvent nozzle is Is a multiple or integer multiple of the distance between the paths, which on the one hand allows a simple spray pattern to be used and, on the other hand, ensures that the solvent nozzle follows the same path as the lacquer nozzle.

In one embodiment of the invention, if more than one lacquer layer is applied on the substrate, the applied lacquer is applied with a solvent after the last lacquer layer has been applied and the last applied lacquer. Layer irregularities and lacquer particles are flattened or removed.

If the last lacquer layer is applied, this lacquer can have a higher solvent ratio than the lacquer of the previously applied lacquer layer. This ensures that until the solvent is sprayed onto the applied lacquer, the solvent proportion of the applied lacquer is not reduced to such an extent that lacquer particles and irregular removal no longer occur.

Even if a single lacquer layer is applied on the substrate, the solvent proportion of the lacquer used is chosen to be higher than in the conventional spray coating process without subsequent solvent spraying.

In one embodiment of the invention, the applied lacquer is repeatedly sprayed with solvent to further improve the surface quality of the applied lacquer.

The solvent may be acetone or methyl ethyl ketone and therefore known solvents may be used.

The object is also achieved by a coating device for applying a lacquer to a substrate, especially a substrate having a topographical feature, which device comprises a substrate holder, a lacquer nozzle, a solvent nozzle, and a lacquer nozzle and a solvent thereon. A moving device in which the nozzles are arranged at a predetermined distance from one another, the lacquer nozzle and the solvent nozzle being able to move together on the substrate holder by means of the moving device. By means of a separate solvent nozzle, which can be moved with the lacquer nozzle, it is possible to spray the solvent onto the lacquer applied on the substrate in the same process step, whereby the lacquer collected on the applied lacquer. The particles can be broken down and the irregularities formed during spraying can be flattened.

Preferably, the coating device comprises a heating device, in particular the substrate holder is provided with a heating element, which makes it possible in a simple manner to reduce the solvent proportion of the applied lacquer.

In one embodiment, the transfer device moves the lacquer nozzle and the solvent nozzle in a parallel path above the substrate holder in at least one plane parallel to the substrate holder and between the lacquer nozzle and the solvent nozzle. The distance is equal to twice or an integral multiple of the distance between the paths.

The distance between the paths corresponds roughly to the diameter of the lacquer jet formed by the lacquer nozzle on the substrate to be covered, so that no position is left on the substrate or it is repeatedly sprayed. The substrate can be applied in a particularly effective way.

While the lacquer nozzle and the solvent nozzle traveled in parallel paths, they were moved by both the solvent nozzle and the lacquer nozzle, or both jets formed by the nozzle, to the edge of the substrate or already beyond the edge. In this case, the distances between the paths are replaced by one another, preferably transversely to the longitudinal direction of the paths.

Adjacent routes have opposite movement directions.

Further advantages and features will be apparent from the following description and the accompanying drawings referred to. The drawings are as follows:

The side view of the coating device concerning this invention is shown typically. The top view of the coating device of FIG. 1 is shown typically. In the method according to the present invention, sectional views of a substrate to be coated at different points in time are schematically shown in ac.

FIG. 1 schematically illustrates a coating apparatus 10 used to coat and handle a substrate. The substrate is, for example, a semiconductor which is subsequently processed further.

The coating device 10 includes a substrate holder 12 and a moving device 14.

On the substrate holder 12 is placed a substrate 16 to be coated with lacquer using the coating device 10.

The substrate holder 12 comprises a heating element 18, which preferably constitutes a heating device for the coating device 10.

The heating element is used to heat the substrate 16 and thereby the lacquer applied on the substrate.

The transfer device 14 comprises two nozzles, a lacquer nozzle 20 and a solvent nozzle 22, which are arranged at a predetermined distance from each other. The distance is the distance between the outlet openings of the lacquer nozzle 20 and the solvent nozzle 22.

The lacquer nozzle 20 and the solvent nozzle 22 are arranged above the substrate 16, ie facing the substrate holder 12 and away from the substrate. As a result, the lacquer nozzle 20 and the solvent nozzle 22 are arranged above the substrate holder 12.

The transfer device 14 also includes an actuator 24, which can be used to move the lacquer nozzle 20 and the solvent nozzle 22.

In the embodiment shown, the lacquer nozzle 20 and the solvent nozzle 22 are moved above the substrate 16 and the substrate holder 12 by means of the movement device 14 along three axes X, Y, Z which extend into the space, In particular, it can move in a plane that is expanded by the X and Y axes. If necessary, further provision is made so that the distance between the nozzle and the substrate is changed, ie the nozzle is adjusted in the Z direction with respect to the substrate.

In particular, the lacquer nozzle 20 and the solvent nozzle 22 are fixedly arranged on the moving store 14 so that the distance between the nozzles 20, 22 does not change. However, it is also feasible to make the distance movable and to use the coating device 10 more flexibly.

To coat the substrate 16, a lacquer nozzle 20 is used to first spray the lacquer onto the substrate 16. In FIG. 3a, the substrate 16 is shown partially before the lacquer has been sprayed.

In Figure 3b, the lacquer nozzle 20 has been sprayed with lacquer at this location on the substrate 16 through the location shown in Figure 3a. A lacquer layer 26 is formed on the substrate 16.

However, the lacquer layer 26, ie the applied lacquer, has irregularities 28 and lacquer particles 30 formed during the spraying of the substrate 16.

To prevent the lacquer formed on the substrate 16 from flowing, the substrate 16 and thus the lacquer layer 26 formed on the substrate 16 is heated. As a result, the solvent evaporates from the lacquer, the solvent ratio of the lacquer decreases and the viscosity of the lacquer increases. The lacquer thus formed is fixed.

The term "set" does not mean that the lacquer is completely dry, but rather that its flowability is reduced to such a degree that it no longer flows in an undesired way. Especially in the case of substrates with vertical terrain features with steep edges and slopes, the applied lacquer will settle as quickly as possible and the applied lacquer will not flow from the edges or higher and Almost no lacquer in position or left with no lacquer.

After the lacquer has been sprayed onto the substrate 16, a solvent nozzle 22 separated from the lacquer nozzle 20 sprays the solvent onto the lacquer layer 26, just past the location where the lacquer was applied.

The solvent jet formed by the solvent nozzle 22 has a limited diameter such that the lacquer layer 26 is sprayed with solvent locally, i.e. in place.

The time between the time when the lacquer is sprayed on one position of the substrate 16 and the time when the solvent is sprayed on this position is constant at each position of the substrate 16.

Due to the effect of the sprayed solvent, the lacquer particles 30 present on the lacquer layer 26 are decomposed and uniformly bond with the lacquer layer 26. Furthermore, the irregularities 28 of the lacquer layer 26 are also planarized.

This forms a flat lacquer layer 26, as shown in Figure 3c.

The lacquer nozzle 20 moves above the substrate 16 to spray the lacquer onto the substrate 16. Movement follows a predetermined path, which causes the lacquer nozzle 20 to move in a predetermined spray pattern.

The solvent nozzle 22 moves simultaneously with the lacquer nozzle 20, but is offset by a distance a. The position of the solvent nozzle 22 relative to the lacquer nozzle 20, in particular the distance a, is chosen to match the spray pattern, so that the solvent nozzle 22 follows the path of the lacquer nozzle 20, thereby moving the same spray pattern.

It is sufficient for the path of the solvent nozzle 22 to correspond to the path of the lacquer nozzle 20 above the substrate 16.

This causes the lacquer and solvent to be applied in the same spray pattern.

To describe the likely spray pattern, the substrate 16 to be applied, the lacquer nozzle 20, and the solution nozzle 22 are described in the plan view of FIG. For clarity reasons, mobile device 14 is not shown.

The broken line shows the path of the lacquer nozzle 20, and the dotted line shows the path of the solution nozzle 22. The positions of the lacquer nozzle 20 and the solution nozzle 22 at the beginning of the coating procedure are indicated by rectangles. The positions of the lacquer nozzle 20 and the solvent nozzle 22 at the end of the coating procedure are indicated by dashed and dotted rectangles, respectively.

The lacquer nozzle 20 and the solvent nozzle 22 are moved by the moving device 14 in a parallel path B above the substrate 16 or the substrate holder 12.

The movement is performed on a surface parallel to the substrate 156 or the substrate holder 12, for example, a surface extending in the X axis and the Y axis.

The height of the nozzles 20, 22 along the Z-axis is chosen above the substrate 16 to be coated, at a distance between the paths B which roughly corresponds to the diameter of the lacquer jet formed by the lacquer nozzle 20.

The diameter of the solvent jet formed by the solvent nozzle 22 preferably has the same diameter on the substrate 16 as the lacquer jet.

In the example shown in FIG. 2, the distance between the lacquer nozzle 20 and the solvent nozzle 22 corresponds to approximately twice the distance b.

Of course, the distance a may be an integral multiple of the distance b.

The path B alternately moves in the opposite direction, for example parallel to the Y axis. Adjacent paths B move in mutually opposite movement directions.

As soon as the jets formed by the lacquer nozzle 20 and the solvent nozzle 22, or the nozzles 20, 22 reach the edge of the substrate 16 or move beyond the edge of the substrate 16, the movement in the Y direction stops and the The two nozzles 20, 22 are offset by the distance b between the paths B along the X axis.

Subsequently, the nozzles 20, 22 are directed in the opposite direction of the previous movement in the Y-direction such that the lacquer nozzle 20 and the solvent nozzle 22 or the jet formed by the nozzles 20, 22 reach the edge of the substrate 16, or Until this is exceeded, it also moves along the Y axis.

The movement of the solvent nozzle 22 is defined by the ratio of the distances a and b and follows the same path B as the movement of the lacquer nozzle 20, which follows the path of the lacquer nozzle 20.

The coating procedure ends as soon as the lacquer nozzle 20 and the solvent nozzle 22 have completely passed over the substrate 16. This means that a jet of lacquer or solvent passes over the entire surface of substrate 16.

The lacquer nozzle 20 and the solvent nozzle 22 are arranged in their final position as represented in FIG. 2 by dashed and dotted rectangles, respectively.

Due to the advantage of the fact that the lacquer nozzle 20 is rigidly connected to the solvent nozzle 22, in the described embodiment the first two paths B of the solvent nozzle 22 are the substrate 16 or the substrate holder 12 at the beginning of the coating procedure. In the plan view adjacent to, while the last two paths B of the lacquer nozzle 20 extend in the plan view adjacent to the substrate 16 or the substrate holder 12 at the end of the coating procedure.

The lacquer is sprayed from the lacquer nozzle 20 and the solvent is sprayed from the solvent nozzle 22 while the lacquer nozzle 20 and the solvent nozzle 22 move over the substrate.

Lacquer is a mixture of solvent and pure lacquer, for example photoresist, the term "lacquer" is understood to mean a mixture of lacquer and solvent.

The solvent used is acetone or methyl ketone. However, other solvents or mixtures of solvents which can decompose the lacquer used are also feasible.

Preferably, the lacquer nozzle 20 and the solvent nozzle 22 are arranged such that the jets formed by them do not overlap on the substrate. Conversely, the jets may be adjacent to each other.

Further, the substrate holder 12 may be heated by the heating element 18 while the lacquer nozzle 20 and the solvent nozzle 22 move over the substrate 16 or the substrate holder 12. In this method, the substrate 16 and the lacquer layer already sprayed onto it are heated.

The coating procedure described, and in particular the spray pattern described in practice, is understood to be merely by way of example. For example, the solvent nozzle 22 can directly follow the lacquer nozzle 20. In this case, the carriers in which they are arranged rotate by 180° at the end of their respective paths, in the following path the solvent nozzles 22 must be arranged behind the lacquer nozzles 20.

Repeated spraying of the solvent on the applied lacquer is also feasible in order to further reduce the number of lacquer particles 30 and the irregularities 28 on the lacquer layer 26.

It is likewise possible that the lacquer and the solvent are sprayed from the same nozzle. In this case, the nozzle repeatedly moves over the substrate, the lacquer being sprayed in one pass and the solvent being sprayed in the other pass.

Of course, it is also possible to apply several lacquer layers on the substrate, in which case the applied lacquer is sprayed with the solvent after the last lacquer layer has been sprayed.

The solvent ratio of the lacquer for spraying the last lacquer layer may be chosen to be higher than the solvent ratio of the previously used lacquer.

In general, if only one layer of lacquer is sprayed, the solvent ratio of the lacquer may be chosen to be higher than in a comparative spraying process without subsequent spraying of solvent.

Claims (17)

A method of coating a substrate (16) with a lacquer, the lacquer being a photoresist, the method comprising:
Spraying lacquer onto the substrate (16) using a nozzle (20) movable above the substrate (16), the movement following a predetermined path, whereby the nozzle (20) is A step of moving over a predetermined spray pattern,
Subsequently, using a movable nozzle (22), viewed including the steps of spraying a solvent lacquer applied to the substrate (16), a
A method characterized in that the solvent is topically sprayed onto the applied lacquer . Between the step of spraying the lacquer and the step of spraying the solvent on the applied lacquer, the solvent ratio of the applied lacquer is reduced to such an extent that the applied lacquer is fixed. The method according to 1 . Method according to claim 1 or 2 , characterized in that the substrate (16) and/or the applied lacquer are heated during and/or after spraying of the lacquer. The lacquer is sprayed on the substrate (16) in a predetermined spray pattern in parallel paths (B) and the solvent is also sprayed in this spray pattern on the applied lacquer. the method according to any one of claims 1 to 3, characterized in that. And when the lacquer in one position of the substrate is sprayed, the method according to any one of claims 1 to 4, the solvent in this position, characterized in that time is constant between the time it is sprayed. The lacquer is sprayed onto the substrate (16) by means of a lacquer nozzle (20) and the solvent is sprayed by means of a solvent nozzle (22) separated from the lacquer nozzle (20). Item 6. The method according to any one of Items 1 to 5 . Method according to claim 6 , characterized in that the lacquer nozzle (20) and the solvent nozzle (22) move above the substrate (16) parallel to the substrate (16) at the same time. Method according to claim 7 , characterized in that during movement of the lacquer nozzle (20) and the solvent nozzle (22), the solvent nozzle (22) follows the path of the lacquer nozzle (20). The lacquer nozzle (20) and the solvent nozzle (22) move in a parallel path (B) above the substrate (16) in at least one plane parallel to the substrate (16), the lacquer nozzle (20) Method according to claim 7 or 8 , characterized in that the distance (a) between the solvent nozzle (22) and the solvent nozzle (22) is equal to twice or an integer multiple of the distance (b) between the paths (B). If more lacquer layer is applied onto the substrate (16), after the last lacquer layer is sprayed, claim 1-9, characterized in that the solvent is sprayed to the coating layer The method described in. The method according to claim 10 , characterized in that, when the last lacquer layer is sprayed, the lacquer has a higher solvent ratio than the lacquer of the previously sprayed lacquer layer. Coated lacquers A method according to any one of claims 1 to 11, characterized in that the solvent is repeatedly sprayed. Solvent A method according to any one of claims 1 to 12, characterized in that acetone or methyl ketone. A substrate (16), a coating device for applying lacquer to a substrate (16) having a topographical shape,
Substrate holder (12), lacquer nozzle (20), solvent nozzle (22), and transfer device on which the lacquer nozzle (20) and the solvent nozzle (22) are arranged at a predetermined distance (a) with respect to each other. Including (14),
Coating device, characterized in that the lacquer nozzle (20) and the solvent nozzle (22) can be moved together above the substrate holder (12) by means of a transfer device (14). 15. Coating device according to claim 14 , characterized in that the coating device (10) comprises a heating device and the substrate holder (12) comprises a heating element (18). A transfer device (14) moves the lacquer nozzle (20) and the solvent nozzle (22) in a parallel path (B) above the substrate (12) in at least one plane parallel to the substrate (12). Designed so that the distance (a) between the lacquer nozzle (20) and the solvent nozzle (22) is equal to twice or an integer multiple of the distance (b) between the paths (B). The coating device according to claim 14 or 15 . The distance (b) between the paths (B) approximately corresponds to the diameter of the lacquer jet formed by the lacquer nozzle (20) on the substrate (16) to be coated . 16. The coating apparatus according to any one of 16 .

Images